The present invention relates to alternating current (AC) to direct current (DC) static converters and, more particularly, to a polyphase converter using multiple rectifier bridges.
In the prior art there are known devices which convert three-phase alternating current by use of twelve-phase rectifier structures to produce a DC output current wherein there is a 30 degree phase shift between the supply voltages of two bridges coupled to produce a direct current output.
According to a known device of the mentioned type, the 30.degree. phase shift between the supply voltages of the two bridges is obtained owing to a three phase transformer having two secondary windings with star-delta or delta-star winding connection. The delta or star primary winding is supplied by the three phase network R, S, T, and the first bridge is connected to one of the secondary windings whereas the second bridge is electrically connected to the other secondary winding. The over-all dimensions of such a transformer of the twelve-phase device are important because they have to be sized up for the total power delivered by the converter.